Prior art satellite terminals are large and expensive. For example, a terminal conforming to the standards known as INMARSAT-M is about the size of a small suitcase and costs approximately $10,000 in 1993. Such a terminal comprises a deployable directional antenna that has to be pointed to the satellite with no intervening obstruction in the line-of-sight, a telephone handset, and a box of electronics and batteries which is coupled to the antenna and to the handset by wires.
Cordless telephones are well known in the domestic context, and allow a user more freedom of movement than conventional telephones. Cellular telephones extend the benefits of wireless communications over wide areas, and can be used in moving vehicles. U.S. Pat. No. 5,428,668 describes an inventive combination of cellular and cordless phone technology which allows the same, cellular handportable telephone to be used both in the wide-area, mobile context, and as a home cordless phone. In addition, the telephone can receive calls either via the cellular system or via the normal home telephone system. In the latter case, the calls are translated to low-power cellular telephone call signals which can be broadcast using the same frequency bands as the wide-area cellular system without causing interference.
The above systems do not disclose translating calls from a satellite communications system into low power cellular call signals in order to receive them using a normal cellular handset.
U.S. patent application Ser. No. 07/967,027 discloses a dual-mode cellular phone capable of operating in an analog FM mode or alternatively in a TDMA Digital speech mode, by using alternative signal processing programs in a programmable digital signal processor. In both cases, the FM or TDMA signal to be processed is received over the air using the same radio hardware.
U.S. Pat. No. 5,535,432 and entided "Dual-Mode Satellite/Cellular Phone With A Frequency Synthesizer" describes a dual-mode satellite/cellular telephone that comprises a satellite RF processing section, a cellular RF processing section, and a common signal processing section that can operate to process either satellite or cellular signals. This device locks preferentially to landcellular signals, if available, and if not, alternatively to satellite signals.
The systems described above, however, do not describe a dual-mode satellite-cellular phone comprising a cellular handset adapted to interface with a satellite adapter unit, wherein said handset receives signal for processing from said adapter unit by means of suitable cables.